1. Field of the Invention
The present invention relates generally to a method and apparatus for creating still picture management data on a rewritable storage media and recording the still pictures on the media, and more particularly, but not by way of limitation, to a method and apparatus capable of reducing the amount of navigation information and index information needed to record still pictures on a rewritable storage media and to a method of grouping still pictures recorded on a recording medium for efficient management.
2. Brief Description of the Background Art
Currently, a great number of optical disks are being used in various fields. With the advent of the DVD (Digital Versatile Disc), it is expected that more and more optical disks will come into use. Optical disks currently include read-only disks such as the CD-ROM and DVD-ROM and record-once disks such as the CD-R and DVD-R. In addition, specifications for rewritable optical disks such as the CD-RW, DVD-RAM, and so forth are under discussion.
Since, rewritable optical disks like the DVD-RAM have very large capacity, they can store a good many moving/still images. When moving/still images are recorded on a rewritable storage media, information for search and retrieval of the images is created and recorded in a navigation information file on the storage media.
The structure of the navigation information file is as shown in FIG. 1, wherein the VOB (Video Object) information field and cell information field are created and inserted in the navigation information file, each time a moving or still image is recorded on the storage media. When reproducing images, the navigation information file is loaded into a memory and a requested moving or still image is searched for and reproduced from the storage media based on the navigation information.
Since still pictures are much smaller in size than moving pictures, a large number of still pictures can be recorded in a storage media—for example, a 4.7 GB storage media can store more than 60 thousand still pictures. Therefore, when a high-capacity storage media is filled with only still pictures, the amount of necessary navigation information increases relative to the stored still images. When a still picture or audio data linked to the still picture is recorded, the two information fields in FIG. 1 (i.e., VOB information and cell information (CT) fields) take up 84 bytes (e.g., S_VOB (36 bytes)+Cell (2×24 bytes)) including the reserved area. In the above example, therefore, the size of the two information fields needed to store 60 thousand still pictures is 5040 KB (84×60000). FIG. 2 shows the relation between VOB information and cell information created when still pictures are recorded.
As a result, even when limited to storage of still pictures, the size of the navigation information file in a storage media exceeds 5 MB. As mentioned above, the navigation information file needs to be loaded into a memory and searched to locate and retrieve a requested still picture from the media; hence a large memory is required merely to store the navigation information temporarily. If the size of the memory is limited, for example less than 512 Kbytes, the number of still pictures to be recorded should also be limited despite the large capacity of the storage media, which is a major problem of the conventional still picture management method.
A disk-type recording medium such as a compact disk (CD) can store high-quality digital audio data permanently, so that it is a very popular recording medium. Recently, a DVD has been developed as a new disk-type recording medium. A DVD can store a much larger quantity of information than a CD. Thus, a high-quality moving picture or audio data can be recorded on a DVD for a much longer time than on a CD. Therefore, DVDs will likely be used more widely than CDs in the near future.
Generally, there are three types of DVDs: DVD-ROMs are read-only DVDs, DVD-Rs are write-once DVDs, and DVD RAMs or DVD-R/Ws are rewritable DVDs. For the rewritable DVDs, a standardization of data writing format is currently being developed.
Recently, Digital Still Cameras (DSCs) capable of storing pictures containing digital data have been developed. Such DSCs usually have a memory chip of large storage capacity so that it can take high-quality pictures and store audio data associated with the stored pictures as well. In a DSC, the taken pictures are encoded in the format of JPEG, or TIFF while the audio data are done in the format of PCM, u-Law PCM, or IMA-ADPCM.
A DSC has a well-known file system called a ‘DCF’ (Design rule for Camera File system) for recording still pictures and audio data. FIG. 3 shows a background art arrangement of a DCF. In the structure of DCF, a DCIM (Digital Camera Images) directory exists under a root directory and many subdirectories may exist under the DCIM. Each subdirectory may have an 8-digit-long filename that is composed of three numeric digits and five character digits, for example. The three numeric digits should be unique, for instance, one among 100 to 999, and the five character digits are arbitrarily chosen by a user. Because the three numeric digits are unique the subdirectories can be created up to 900.
A subdirectory, e.g., subdirectory ‘100ABCDE’ of FIG. 3 can accommodate many data files of which a filename may be 8-digits long. The filename may be composed of four numeric digits and four character digits, for example. While the four character digits are chosen by a user the four numeric digits should be unique among data files if their attributes are different. The data files are still pictures and/or audio files, respectively. The still picture files typically have an extension of ‘JPG’ or ‘TIF’ with their filenames while the audio files encoded by PCM, u-Law PCM or IMA-ADPCM typically have an extension of ‘WAV’ with their filenames. The filenames of the data files can be same if their extensions are different. Therefore, when a picture file is to be dubbed with audio, a dubbed audio file can be linked with the picture file only if their filenames are the same.
A digital video recorder (DVR) records video and audio data in a background art file structure shown in FIG. 4. The file structure of FIG. 4 has a DVR directory under a root directory. The DVR directory includes a menu file ‘menu.tdat’, a mark file ‘mark.tdat’, and their index files ‘menu.tidx’ and ‘mark.tidx’. The menu and the mark files have menu data and mark data respectively and the index files have search data to index menu and mark data in the menu and the mark file.
The ‘DVR’ directory is mandatory for motion picture recording of a DVR. The ‘DVR’ directory has directories ‘PLAYLIST’, ‘CLIPINF’, and ‘STREAM’. The ‘PLAYLIST’ directory includes playlist files (*.rpls,*.vpls) containing motion-picture and still-picture play items and title management information. The directory ‘CLIPINF’ includes clip information files (*.clpi) containing information on movie stream management and movie attribute. The directory ‘STREAM’ includes stream files (*.m2ts) containing actual motion-picture data stream packets.
However, many still pictures obtained with a DSC under the file system of FIG. 3 are moved to a recording medium of very large capacity because of relatively small storage capacity of a DSC. That is, numerous still pictures taken by a DSC will be recorded onto a large-capacity recording medium through a DVR capable of recording data onto that medium. This fact strongly demands a DVR that uses an efficient still-picture management method.